1. Field of the Invention
The present invention relates to a speech recognition system capable of allowing electronic equipments to be controlled or manipulated with uttered voices or speeches, and a speech recognition method for use in such a speech recognition system.
2. Description of the Related Art
Known speech recognition systems of this type are adapted to electronic equipments, such as an on-board audio system and an on-board navigation system.
In an on-board audio system equipped with a speech recognition system, when a passenger says the name of a desired radio broadcasting station, for example, the speech recognition system recognizes the uttered speech and automatically tunes to the reception frequency of the radio broadcasting station based on the recognition result. This improves the operability of the on-board audio system and makes it easier for a passenger to use the on-board audio system.
This speech recognition system also has other capabilities that relieve a passenger of the burden of operating an MD (Mini Disc) player and/or CD (Compact Disc) player. When the passenger loads an information-carrying recording/reproducing medium, such as an MD disc, into the MD player and says the title of a musical piece recorded on that recording/reproducing medium, for example, the speech recognition system recognizes the uttered speech and automatically plays the selected musical piece.
An on-board navigation system equipped with a speech recognition system is provided with a capability of recognizing a speech uttered by a driver or the like to specify the name of the destination and displaying a map showing the route from the present location to the destination. This capability allows the driver to concentrate on driving a vehicle, thus ensuring safer driving environments.
The above-described conventional speech recognition systems are designed to cope with a single person who utters words of instructions. The conventional speech recognition systems therefore have only a single microphone for inputting speeches provided at a location nearest to a driver who is very likely to use the microphone.
Other passengers who are seated far from the microphone should therefore utter loud voices toward the microphone to secure a sufficient input voice level. To improve the speech recognition precision of such a speech recognition system, other passengers than the driver should also utter loud voices toward the microphone to input uttered speeches into the microphone without being affected by noise in a vehicle.